To Prepare Fish: Using paper towels, pat fishdry. In small nonstick skilletcombine water, lemon juice, and seasonings and bring to a boil. Reduce heat and add fish; cover and let simmer until fish flakes easily when tested with a fork, 1 to 2 minutes. Using slotted spoon, remove fish to a bowl; set aside. Discard cooking liquid.

To Prepare Sauce: Wipe same skilletclean; add oil and heat. Add onion and cook until translucent. Sprinkle with flour and stir quickly to combine; cook, stirring constantly, for 1 minute. Gradually stir in water; add lemon juice, sugar, vinegar, and seasonings and, stirring constantly, bring to a boil. Reduce heat and cook until mixture thickens slightly. Pour sauce over fish and gently toss to combine; cover with plastic wrap and refrigerate until chilled. Just before serving, toss again and garnish with lemon and parsley. Makes 2 servings.